In recent years, from a viewpoint of energy saving, an illumination device (for example, an LED bulb) including a light source in which an LED is employed has been used. However, the light source employing an LED has a problem of a small light distribution angle due to its structure or a directivity of emitted light. In view of this, various illumination devices having configurations for improving its light distribution characteristics have been proposed.
For example, Patent Literature 1 describes an ultra-wide light distribution LED lump which is capable of improving its light distribution characteristics. FIG. 20 is a cross sectional view showing a configuration of an ultra-wide light distribution LED lamp 2000 described in Patent Literature 1. The ultra-wide light distribution LED lamp 2000 includes a substrate 2001 in which metal frames 2002 and 2003 are insert-molded, an LED chip 2004 provided on the substrate 2001, and a light transmissive plastic cover 2005 which shields the LED chip 2004.
The LED chip 2004 is provided on a top flat surface 2007 of a projection part 2006 which is formed at a part of the metal frame 2002. The top flat surface 2007 is configured to be higher than a surface of the substrate 2001. In the ultra-wide light distribution LED lump 2000, a light distribution angle is widened by providing the LED chip 2004 at a highest position, whereby light distribution characteristics are enhanced.
Furthermore, Patent Literature 2 describes a bulb illumination device from which luminous intensity can be obtained in a desired direction on a basis of a situation. FIG. 21 is a cross sectional view showing a configuration of a bulb illumination device 2100 described in Patent Literature 2. The bulb illumination device 2100 includes (i) a main body provided with an electronic supply base 2101 at its one end and a block shaped protrusion part 2102 protruding in a direction of a rotation axis of the electronic supply base 2101 at the other end, (ii) a plurality of light-emitting modules 2103 provided on various points on an outer surface of the protrusion part 2102, (iii) a circuit section 2104 which selectively turns on the plurality of light-emitting modules 2103, and (iv) a globe 2105 which covers the plurality of light-emitting modules 2103.
In the bulb illumination device 2100, the plurality of light-emitting modules 2103 provided on various points on the outer surface of the protrusion part 2102 are selectively turned on by the circuit section 2104. This makes it possible to switch over a plurality of light distribution patterns each having a luminous intensity peak in a different direction. With this configuration, light distribution characteristics are improved.